DADA Luke Castellan
by kaboomblahstick
Summary: Luke Castellan wants to get into Elysium, and is willing to do anything for that. Harry Potter and Ron is dragged by Hermione back to Hogwarts for their 7th year and they get a strange new DADA teacher. And somehow, this is all related?
1. LUKE Ghosts Give Gifts

He stepped through the darkness of the Underworld.

To his right, were the Fields of Asphodel, bland, and devoid of any colour. To his left, were the Fields of Punishment. Screams of agony could be heard even here where he was, at the Judgement Pavilion. The young ghost winced at the thought of the suffering. He once had sandy blonde hair. It was now grey. He once had compelling blue eyes. They were now grey. He had an ugly scar running down the side of his face. It seemed as grey as ever. And so was his future. There is a fine line between being a hero and villain, and he was standing on it right now. As he stepped onto the Judgement Pavilion, dread filled his mind.

_Elysium_, he thought. _Think positive. Think Elysium_.

But he knew there was _also_ an equally good chance that he would end up in the Fields of Punishment.

"Name?" asked the ghost of a bored old man. It was King Minos, one of the Pavilion judges.

"Luke Castellan," he responded. "Son of Hermes."

* * *

><p>Luke watched as some of the other members of the Pavilion judges appeared. Famous men he recognized from the boring history books he never bothered to read. At first glance they seemed grey, like most of the other shades he'd seen around here, but on closer examination, he could almost, <em>almost<em> see the colours tinted against their transparent bodies. There were three of them in total, including old Minos, and they sat regally in front of him, their eyes devoid of any emotion.

In Mino's hands appeared a stark grey folder, with a crayon scribbled "Castellan" on the cover. He flipped through the page quickly. "Mmh, impressive resume," he muttered, as he showed the contents of the folder to the fellow judges. "BUT –" Minos slapped the folder closed with force and a sudden change of demeanour, "–we'd like to hear the story from _you_. _No_ lies, and _no_ leaving any parts out. First and second strike, you get Fields of Asphodel. Third strike's Fields of Punishment. Understand, hero?"

Luke simply nodded. And so he started to tell the story of his life.

He started with his birth, a son of Hermes and a mortal, May Castellan. He spoke of his mother with disgust, of her ongoing rambles about his fate and whatnot, and him finally running away at nine when he absolutely couldn't stand her anymore. He talked about Thalia, about Annabeth, about camp. And then came his father Hermes and his failed quest at Camp Half-Blood, which had began to fuel his hatred of the gods

Luke wanted to leave the next part out, about his realignment, siding with Kronos, but he knew he couldn't hide anything from the judges if he wanted to get into Elysium. So he continued on about Percy Jackson. About stealing the Master Bolt. Poisoning Thalia's tree. Helping capture Artemis. Giving up his body for Kronos. All the bad things he regretted to have done. Tears streamed down his ghostly face whenever he mentioned Annabeth, like somebody repeatedly stabbing a knife into his Achilles heel under his arm. Finally, when he was almost out of breath, he uttered, "I... I knew Kronos... he would destroy the world i-if he reached his full form. So..." He choked on the last words, "So I stabbed myself on my Achilles spot, and... he was destroyed... and that was how I died."

By now, Luke's body looked as grey as ever. He knew this wasn't a good sign, but he had to stay strong. _Elysium_, he kept thinking. _Please_.

He was studied intently for a while, while Minos flipped unemotionally through the folder again, occasionally muttering inaudible phrases. Finally, he asked, "What do you think, Jeff? Should we throw him in the lava and let the 40s music deal with him?"

The man he called "Jeff," probably former President Jefferson, shook his head, frowning, though Luke couldn't tell if it was because he disagreed with Minos, or disgusted with what Luke had done. The third ghost judge, leaned in and whispered something to both Minos and Jefferson. While Minos' brow furrowed at the idea, Jefferson nodded soundly, almost with a smile.

"You can't just –" Minos blared out.

"Silence," said Jefferson. "Will here has made an excellent proposal. All in favour?"

Jefferson and the guy he called Will raised their hands.

"Democracy, pah!" complained Minos. "Who the heck invented this crap?"

"The Greeks," answered Luke, who was starting regaining his composure after his meltdown. "And _what_ exactly is this "proposal" you talk about?"

To answer his question, the Will guy snapped his fingers, and another ghost appeared. The new arrival looked young, no older than Luke himself, but he wore some kind of strange clothing – an emerald cloak, and a weird pointed hat. The ghost reached inside his pockets and took out a foreign object Luke didn't exactly recognize. It was a golden necklace, except for the fact that there was a tiny hourglass in the middle. "Wear the time turner," he explained, handing it to Luke. "It is a very delicate instrument, so be careful when handling it. Don't let any man know you have possession of such an ornament. I had it professionally enchanted so it will turn back time for 11 years, and you will be granted a life... _temporarily_." Then the ghostly young man bowed to the Judges, and floated away to join the other wandering shades.

Jefferson nodded with satisfaction. "You will be sent back to England, 1998, where you shall act for one year as an instructor for..." he paused "...for a school of clear-sighted mortals. When you finish your quest – _if_ you finish your quest – you will be considered for Elysium. Fail, and it is the Fields of Punishment in lava and listening to 40s music. Understand?"

Luke's eye twitched. _England 1998?_ He thought._ School of clear-sighted mortals? Was this some kind of joke?_ He wanted to throw this time-turning – whatever – at these ghosts, but still, he knew better than to argue with them. He knew he deserved _at least_ the Isle of the Blest, but first, he will need to get into Elysium, and if _this_ is the best deal he's getting, he'd better accept it. "I understand," he said, kneeling in front of the judges.

"Good," said Minos. Then that guy... Will, uttered some word he didn't catch while pointing a strange wooden stick at him, and the Underworld swirled into complete darkness.

* * *

><p>When Luke woke up, he had a solid body again.<p>

Was it all just a dream? Kronos, and the Titan war? Maybe he was back inside Cabin Eleven, with all his half brothers and the unclaimed campers.

But this place was... unfamiliar? He had no idea where he was. The room wasn't big, but he hadn't had the luxury of sleeping in a real _room_ for a long, long time. His sheets were made of cotton, and they felt like the best thing ever. Luke sat up abruptly as he realized something. No noise. No chatter. This room was completely silent, an experience he haven't had a chance to experience for almost his whole life.

He got out of bed and stretched. It was nighttime, for all he could tell. On his body, he wore celestial bronze battle armour, forged to perfection. Underneath that was a normal white t-shirt and jeans. Something brushed against the side of his thigh as he tried to move, and looking down, he saw the hilt of a weapon sheathed by his side.

A familiar weapon.

He grasped the leather handle and pulled the gleaming celestial bronze knife out. The worn hilt was stained with specks of dried blood, but the blade remained as sharp as ever. _The cursed blade_, Luke thought. Carefully, he brushed the edge of the knife to his fingers, and sure enough, blood flowed swiftly out of the light cut. His Achilles heel must have been taken away from him. Then again, maybe he didn't _have_ an Achilles heel to _start with_. But the spot under his arm still tingled as he stroked it. His memory of the bathe in the River Styx was vivid, as if it were only yesterday.

But Luke had more pressing problems. For example, where _was_ he?

Suddenly, he heard an abrupt rapping on his door. And again. "Open up, Professor Castellan!" yelled an authoritative female voice. "It's time for the feast!"


	2. HARRY Return to Hogwarts

**A/N: I pretty much had half a mind to abandon this fanfic (partly because I forgot about it), so thanks to daughterofthehunt for reminding me to update. (A LOT.) I'm not sure if you guys will be able to notice from my writing, but first, I have NOT reread HP 5-7 in a LONG time, so I was pretty much abusing the heck outta the Harry Potter wikia while struggling to remember stuff. And second, I haven't written in a long time as well, so... hopefully you think it's okay, whoever that reads this. Oh, and sorry again for not updating for such a long time. -kbs**

* * *

><p>"You still have the chance to turn back now," said Hermione Granger, pausing in front of her carriage.<p>

Harry shook his head, even though he knew she couldn't see him. "I'm dead set on this. _Right_, Ron?"

Only a groan was heard behind him as Harry Potter struggled to climb onto the thestral. It was a tough fit for both boys and the invisibility cloak nearly slipped off, but luckily, they got off the Hogwarts Express early so nobody spotted them. They waited anxiously for the carriages to fill up, with Harry hoping for good company. Luckily, it was Ginny and Luna who claimed the empty spots, and he sighed in relief. It wouldn't be likely for either of them to rat him out or ask for his autograph. (Probably because Ginny was in on their plan. Harry wasn't entirely sure about Luna, though.) Soon, the thestrals leaped into the air, and they were off to Hogwarts.

"Remind me why we're doing this again?" asked Ron, who sat in front of Harry on the thestral.

"I really don't want to attract that much attention after what happened... you know, last summer."

Ron sighed. "What's it got to do with me? I would have liked the attention. Why does Hermione get the attention instead of me?"

Hermione's head poked out of the front window. "In your own words, Ron Weasley, _'Six years of education was plenty!'_ That was, until _I_ mentioned I was going to retake my seventh year and suddenly you're tagging along."

"Harry could have pulled some strings. I'm sure they'd let me—"

"Shut up, Ron," said Harry, who was starting to feel a little irritated. "I don't want to hear everybody arguing..."

"Hermione's the one that's arguing— Harry, are you alright?"

No response came from Harry. He was too busy fighting a feeling, a sudden surge of... depression? Carefully, without revealing himself from under the invisibility cloak, he took out his wand. "_Expecto Patronum,_" he whispered, trying to cast his patronus as quietly as possible. But he wasn't particularly focused on the happy thoughts, as only a small whisp appeared from the tip of his wand.

Moments passed before Hermione whispered, "What are you doing?"

"I don't know," said Harry. "Uh, maybe... trying to get rid of the dementors without giving myself away?"

"Dementors? Harry, _are you all right?_"

Harry didn't like the way Hermione said those words. "You sound just like Ron! I'm fine, just leave me alone!"

"Harry..."

He was about to wave her away, when he realized Ginny was speaking to him this time.

"Calm down," she said, stepping to the front of the carriage. "You're not acting like yourself."

"I know!" he shouted, or at least, as loud as he can shout while whispering. "That's why—"

Ginny handed Harry her hand. Reluctantly, Harry took it, even though his was invisible. "Just calm down," she said, soothing his emotions. "Believe me, there are no dementors, or we would have noticed. Harry, you are just stressed out, so calm down."

He was still skeptical, but Harry was willing to listen to Ginny. Still, he asked, "Are you sure..."

"_Yes,_ I am _sure_. I grew up with _Ron_, of course I'm sure."

Ron took that as an invitation to butt into the conversation. "Gee, thanks, sister, never knew you were into counselling."

Ginny raised an eyebrow. Then she climbed back into her seat. "Though I usually wouldn't advocate violence at a time like this, feel free to slap my brother as hard as you like."

Harry smiled, feeling a bit better. It wasn't until they were almost at Hogwarts when he glanced at the seat next to Ginny, where Luna Lovegood was sitting. She didn't seem to have noticed Harry and Ron's prescence even after their little four-way shouting match with Hermione and Ginny. (Or at least, Luna didn't make any _indication_ that she had noticed anything.) Ron would say Luna Lovegood was loony in the head, even after all this time, but Harry appreciated a friend who doesn't question the weird things that always seemed to happen around Ron, Hermione, and him.

* * *

><p>It was surreal being back at Hogwarts, even though the place was absolutely trashed after the battle. Only so much could be mended with magic, and according to Ron, <em>"It looks cooler now anyways."<em> However, Harry wondered if the school would ever return to how it was before; deep inside him, he knew the answer was no.

The house tables in the Great Hall were noticeably less crowded than the years before that he attended, which allowed Harry and Ron to sit down in an empty space between Hermione and Ginny without too much suspicion. Harry supposed it should be taken as a bit of good luck, but he wondered about the many students that weren't there that year. _The war just ended,_ he said to himself. _Surely, some of the parents won't feel safe sending their children back, not yet. Maybe eventually..._ Of course, those weren't all of them. There were also the students who had died in the battle. Not everybody was coming back.

Harry's eyes wandered to the staff table. He wondered about the new staff coming in. There were the usual: Hagrid, Professor Sprout, Flitwick... and surely McGonagall was to be the new Headmistress. But there were also a few witches and wizards he didn't recognize, including who he assumed to be the new Defence Against the Dark Arts professor, a blond fellow with hastily-put-on robes who hurried toward the staff table. For some reason, the professor reminded Harry of Cedric Diggory. In fact, he was extremely young, probably the same age as Cedric would be now... had he had lived.

His thoughts were interrupted, however, when the first years filed into the hall from their trip across the lake. The eleven-year-olds were dripping wet and their eyes stared as the Sorting Hat was brought out. The hat was in worse shape than ever, though Harry found it surprising to see it had survived from being burnt to ashes. Albeit being magical, it was still a hat, not a phoenix.

The murmurs in the Great Hall died down to a disconcerting silence. And so the Sorting Hat began its new song:

_Through all the years I've sat and watched  
>As Hogwarts took its toll<br>This ancient hat never did expect  
>To play an active role<em>

_You look at me and start to think  
>I'm about to fall apart<br>Well yes that's true, I agree with you  
>But I stay strong in my heart...<em>

"Hey, Harry," Ron whispered into his ear.

"What?"

"D'you suppose we have to go to class? Seeing as nobody knows we're students..."

Harry sighed. He tried to come up with an answer while keeping an ear for the Sorting Hat's song. "Isn't that the point of going to school? To learn?"

"Yes, but can't we just learn from Hermione?"

Annoyed, Hermione nudged Ron hard, and he stopped talking. Harry quickly turned his attention back to the Sorting Hat, slightly angry at Ron interruping through most of the song. At least he could still catch the ending...

_A new generation walks in again  
><em>_While the old walk out  
><em>_Hogwarts' rebirth begins  
><em>_But lingering is old doubt_

_Come to me and I will see  
><em>_Your future, clear and true  
><em>_Restore the world its former glory  
><em>_Now let's begin with you!_

* * *

><p><em><em>**P.S. I was tempted to name this chapter "Get Back to Hogwarts". . .**


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